Phenomena of neurobiotaxis in the optic system 283 



of smaller cells in the fronto-dorsal part of the III complex, may be 

 distinguished (in Lizards). The división in birds is still much more con- 

 spicuous, as has been first demonstrated by 5". Ramón y Cajal, and as also 

 appears from figure 16, a photo made by my collaborator Dr. Vermeulen. 

 I can also confirm the statement of S. Ramón y Cajal and Mesdag that 

 in birds, we find a large accessory niicleus composed of small cells, such 



Xu. ac- 

 cess. (Ed. ""] 

 Westph.) 



Nu. dorso- 

 lat. 



Xu. dorso- 

 iiiet. 





Fig. 16. — Oculomotor nucleus ¡n the adult Chick. Microphotogramm by Dr. Vez- 

 meulen Note the presence the Nu accessorius III (nucí. Edinger-Westphal) and the 

 absence of a central nucleus of Perlia (comp. fig. 19 Homo, where Perlia's nucleus 



is present). 



as in man has been first described by Edinger and Westpiíal. This ac- 

 cessory nucleus in birds (fig. 16), acquires very considerable dimensions' 

 probably in connection with the fact that the internal eye-muscles are 

 sostrongly developed here. Its rootfibers are thinner than those of the 

 somatic oculomotor fibers and lie laterally to the latter at the emergence 

 of the root [Carpcnter) running to the ciliary ganglion. The number ot 

 crossed root-fibres has increased. 



Concerning the origin of these crossed root-fibres in birds, Biondi 

 gave interesting informations pointing to a neurobiotactic shifting appa- 

 rently caused by controlateral inñuences acting on the cells. 



